Conventionally, a lamp annealing apparatus using a flash lamp, which is used for heat processing in semiconductor manufacturing or thin film transistor manufacturing, has been developed. For example, such a lamp annealing apparatus is used in a process for forming a shallow diffusion layer (p-n junction) in a silicon wafer surface layer (impurities activation for implanting ions). In this annealing process, it is necessary to avoid problems such as deformation of the profiles of ion-implanted impurities, and volatilization of the formed pattern, so as to acquire a good activated state of the impurities. Therefore, in this lamp annealing apparatus, it is necessary to suppress conduction of heat to lower part of a base plate, and to uniformly and certainly heat it to predetermined temperature. Similarly, in a thin film transistor manufacturing for a liquid crystal display panel, it is necessary to activate a semiconductor film formed on a base plate certainly and uniformly. It is required to suppress generation of expansion and contraction of a base plate or warpage thereof by preventing excessive heating to the base plate while accomplishing an annealing treatment, specifically in case where the base plate is made of glass.
In recent years, a flash lamp with a larger amount of light is demanded because the area of a semiconductor base plate or a glass base plate for a display becomes much larger (from (φ300 to φ450, and G4 to G10), and because usage thereof is expanded to other fields. Then, an increase of the amount of irradiation light from a lamp has been tried by providing a reflective film on an arc tube. A conventional technology, in which such a reflective film is formed on an arc tube of a flash lamp, is disclosed in Japanese Patent Application Publication No. 2002-014393. FIG. 6 shows the structure thereof, wherein the reflective film 12, which is made from a metal vapor-deposited film, is formed on part of an outer peripheral surface of an arc tube 11, and a heat radiating member 13 is provided thereabove. However, this technology relates to a low output flash lamp for a camera, and since, in a high output flash lamp which is used for a heat process, a thermal load is extremely large with respect to a reflective film, this technology cannot be applied to some other purpose as it is. That is, in the case of such a reflective film, which is made from a metal vapor-deposited film disclosed in Japanese Patent Application Publication No. 2002-014393, the film is overheated, and is oxidized or sublimated by a high-output lamp, so that there is a problem that the reflection function of the reflective film will be deteriorated by lighting the lamp even for a short time.
On the other hand, further improvement in lighting startability of such a flash lamp is also required. For example, Japanese Patent Application Publication No. 2004-303889 discloses technology in which a metal wire called a trigger wire on the outer surface of a flash lamp is provided, thereby improving the lighting startability of the lamp.
As a means for preventing damages to the reflective film disclosed in Japanese Patent Application Publication No. 2002-014393, it is considered that the constituent material of the reflective film may be changed from the metal vapor-deposited film to a ceramic material having higher heat resistance. However, although the problem due to the overheating is solved by using the ceramic material, if it is applied to a flash lamp having a trigger wire as disclosed in Japanese Patent Application Publication No. 2004-303889, there is a problem that the function of this trigger wire is impaired so that the lighting startability will get worse. The causes thereof are considered as set forth below. Although the trigger wire is formed outside the arc tube, this trigger wire is provided on a non-emission side of the arc tube, that is, on a side where the reflective film is formed, due to relation thereof with an output light. That is, since the reflective film will lies between the trigger wire and the arc tube, the electrical insulation properties of the arc tube and the trigger wire is increased by the reflective film, which is made from ceramic material, whereby even if voltage is applied to the trigger wire, it does not effectively act on the arc tube, so that the startability of the lamp will be prevented. Thus, the reflective film, which is made of ceramic material, causes a decrease of the trigger function, and worsens the startability of the lamp.